Arrange four 12-inch squares aluminum foil on work surface. Divide potato mixture among foil squares and place 1 garlic clove atop potatoes on each square. Crimp to seal. Store packets at room temperature up to 2 hours or in refrigerator up to 2 days.

Prepare barbecue (medium-high heat). Place potato packets on grill and cook until heated through and sizzling, turning occasionally, about 15 minutes. Transfer packets to serving plate and pierce foil with grill fork to release steam. Open packets carefully (hot steam will be released).